TY - JOUR
T1 - Synergistic induction of osteocalcin gene expression
T2 - Identification of a bipartite element conferring fibroblast growth factor 2 and cyclic AMP responsiveness in the rat osteocalcin promoter
AU - Boudreaux, J. M.
AU - Towler, D. A.
PY - 1996/3/29
Y1 - 1996/3/29
N2 - Fibroblast growth factors (FGFs) are important regulators of calvarial osteoblast growth and differentiation. We have studied the regulation of the osteoblast-specific gene osteocalcin (OC) by FGF2 in phenotypically immature MC3T3-E1 calvarial osteoblastic cells. FGF2 markedly induces OC mRNA accumulation in MC3T3-E1 cells in the presence of forskolin (FSK). Similarly, OC promoter activity (luciferase reporter) is up-regulated 6-10-fold by FGF2/FSK or by FGF2/8-bromo cyclic AMP. Half-maximal induction of OC promoter activity occurs at 1 nM FGF2. By 5′ deletion analysis and dinucleotide point mutations, we map one component of this FGF2/ FSK response to a GCAGTCA motif in the region -144 to - 138 relative to the OC transcription initiation site. The OC promoter region -154 to -90 confers FGF2/FSK responsiveness on the Rous sarcoma virus minimal promoter. By 3′ and internal deletion analyses, the region between -90 to -99 is also found to be necessary for FGF2/FSK synergy (encodes a PuGGTCA motif previously identified as a component of FSK induction). A DNA binding activity that recognizes the region -148 to - 125 of the rat OC promoter is induced in crude nuclear extracts from MC3T3-E1 cells treated with FGF2 or FGF2/FSK. This binding activity is sequence-specific and does not recognize the TCAGTCA DNA cognate of API. Members of the ATF, Fos, and Jun family are not immunologically detected in this inducible DNA binding activity. However, transient co-expression of ATF3 but not ATF2 selectively attenuates the FGF2 component of induction. Thus, a novel FGF2-regulated DNA-protein interaction in the OC promoter participates in the transcriptional control of OC expression by FGF and cyclic AMP in MC3T3-E1 calvarial osteoblasts.
AB - Fibroblast growth factors (FGFs) are important regulators of calvarial osteoblast growth and differentiation. We have studied the regulation of the osteoblast-specific gene osteocalcin (OC) by FGF2 in phenotypically immature MC3T3-E1 calvarial osteoblastic cells. FGF2 markedly induces OC mRNA accumulation in MC3T3-E1 cells in the presence of forskolin (FSK). Similarly, OC promoter activity (luciferase reporter) is up-regulated 6-10-fold by FGF2/FSK or by FGF2/8-bromo cyclic AMP. Half-maximal induction of OC promoter activity occurs at 1 nM FGF2. By 5′ deletion analysis and dinucleotide point mutations, we map one component of this FGF2/ FSK response to a GCAGTCA motif in the region -144 to - 138 relative to the OC transcription initiation site. The OC promoter region -154 to -90 confers FGF2/FSK responsiveness on the Rous sarcoma virus minimal promoter. By 3′ and internal deletion analyses, the region between -90 to -99 is also found to be necessary for FGF2/FSK synergy (encodes a PuGGTCA motif previously identified as a component of FSK induction). A DNA binding activity that recognizes the region -148 to - 125 of the rat OC promoter is induced in crude nuclear extracts from MC3T3-E1 cells treated with FGF2 or FGF2/FSK. This binding activity is sequence-specific and does not recognize the TCAGTCA DNA cognate of API. Members of the ATF, Fos, and Jun family are not immunologically detected in this inducible DNA binding activity. However, transient co-expression of ATF3 but not ATF2 selectively attenuates the FGF2 component of induction. Thus, a novel FGF2-regulated DNA-protein interaction in the OC promoter participates in the transcriptional control of OC expression by FGF and cyclic AMP in MC3T3-E1 calvarial osteoblasts.
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U2 - 10.1074/jbc.271.13.7508
DO - 10.1074/jbc.271.13.7508
M3 - Article
C2 - 8631781
AN - SCOPUS:0029918116
SN - 0021-9258
VL - 271
SP - 7508
EP - 7515
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 13
ER -